<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <link rel="stylesheet" href="base.css">
    <style>
    *{margin: 0;padding: 0;}
    html,body{
        height: 100%;
    }
    .web{
        height: 100%;
        display: flex;
        flex-direction: column;
    }
    .top{
        
        height: 1.5625rem;
        background: red;
    }
    .center{
        flex: 1;
        overflow-y: auto;
        background: #ccc;
    }
    .buttom{
        height: 1.5625rem;
        background: red;
    }
    </style>
    </head>
<body>
    <div class="web">
<div class="top"></div>
<div class="center"></div>
<div class="buttom"></div>


    </div>
</body>
<script src="rem.js"></script>
</html>